Air lift jack

ABSTRACT

A lift jack is powered by compressed air and is sealed against the admission of dirt and water into the air cylinder. The air cylinder is provided with a bottom wall or base having a normally convex curvature that becomes concave, in an &#39;&#39;&#39;&#39;oil can&#39;&#39;&#39;&#39; effect, when the jack is placed under load and compressed air applied to the piston within the air cylinder. Convex curvature of the bottom wall allows the relatively heavy lift jack to be moved along on a floor plane more easily and with less effort, and with no damage to the floor surface. An extensible member, adapted to be pin-connected to the main lift cylinder, is also provided to increase the lift height of the jack. The upper surface of the air cylinder is arranged with radial corrugations, to provide great strength and rigidity and to eliminate material deflection of the lift cylinder in load lifting operation. A lift handle is fixedly secured to the main cylinder of the jack for easier portability and in such attitude that the entire unit is carried in a more balanced manner, without injury to the person carrying the jack or damage to the jack.

United States Patent 91 Ekonen et al. 1 May 1, 1973 AIR LIFT JACK [76]Inventors: Martin A. Ekonen, 29581 Puritan [57] ABSTRACT Avenue,Livcmia, Mich- 48154; A lift jack is powered by compressed air and issealed Stanley Dupras, 15383 west Blue against the admission of dirt andwater into the air Skies Court Livonia, Mich-48152 cylinder. The aircylinder is provided with a bottom [22] Filed; May 19, 1971 wall or basehaving a normally convex curvature that becomes concave, in an oil can"effect, when the PP N05 144,778 jack is placed under load and compressedair applied to the piston within the air cylinder. Convex curvature 52U.S. Cl. ..254/93 R of the bottom wall allows the relatively heavy liftj [51 rm. Cl. .B66f3/24 to be moved along on a fleer plane more easilyand [58] Field of Search ..254/93 HP, 93 R, with less effort, and withno damage to the fl 254/93 M, 133, 1; 248/350, 357 face. An extensiblemember, adapted to be pin-connected to the main lift cylinder, is alsoprovided to in- [56] References Cited crease the lift height of thejack. The upper surface of the air cylinder is arranged with radialcorrugations, to UNITED STATES PATENTS provide great strength andrigidity and to eliminate 3,567,183 3 1971 Voss ..254/93 HP materialdeflection 0f the lift cylinder in load lifting 2,380152 7/1945 David..254/93 HP operation. A lift handle is fixedly secured to the main1,248,861 12/1917 Holloway ..254/93 HP cylinder of the jack for easierportability and in such 3,361,408 1/1968 Strang et a1 ..254/2 R attitudethat the entire unit is carried i a more Primary Examiner-Othell M.Simpson Assistant Examiner-Robert C. Watson AttorneyBenjamin W. Colmanbalanced manner, without injury to the person carrying the jack ordamage to the jack.

10 Claims, 5 Drawing Figures AIR LIFT JACK The invention involves anair-operated piston in a cylinder having an oil can type bottom plate, aradially corrugated top plate cover member, formed as a casting andhaving a hub section extending into and secured to the main aircylinder, a piston having an outer perimeter slightly spaced from theinner wall surface of the air cylinder and provided with a medialannular seal of substantial thickness so that at 180 psi, the air jackis capable of lifting at least 13,500 pounds of load. An axial liftcylinder is secured to the piston, with a removable lift pad at itsdistal end. The bottom of the piston is provided with a spacing pad ofsuch height that when the piston is at rest on the bottom plate, a spaceis provided for admission of compressed air under the piston, thefitting connecting the air supply conduit to the air cylinder beingsecured adjacent the bottom edge of the air cylinder at the bottomplate.

A significant and critical factor, in addition to the features describedabove, is an upper cover for the air cylinder, in which the over-allheight of the lift cylinder bearing, which is integrally formed with thecover member in a casting, includes an outer peripheral hub sectionadapted to be secured within and to the upper end of the air cylinder, aflange extending outwardly from the hub section to overlie the edge ofthe air cylinder, a radially corrugated top plate cover portionproviding great strength against distortion to the cover member, and acentral axial hub section or bearing having a seal within its bore toexclude dirt, water and other deleterious matter that may find itselfupon the outer surface of the lift cylinder which rides within the boreof the cover member. The radially corrugated cover surface tapersupwardly from the peripheral flange to substantially increasethe,,.over-all height of the bearing and provide maximum support of thelift cylinder against deflection and pivoting.

The air cylinder is also provided with a tapering coiled spring adaptedto hear at its base upon one side of the piston and at its other endagainst the inner surface of the radially corrugated upper end walladjacent the lift cylinder, to bias the piston to seated position uponthe bottom plate when air is released and discharged from the aircylinder. 7 g

The air lift jack of this invention is adapted to be supplied withcompressed air furnished by any suitable upon the main lift cylinder inthe distal end of the supplementary lift cylinder.

The handle of the lift jack is a substantially semi-circular ring havingits ends fixedly secured to the outer wall of the air cylinder so. thatwhen the jack is lifted readily moved on a floor surface. Still anotherobject is to provide an air lift jack that is extremely sturdy ofconstruction, of substantially high lift capacity, safe and simple tooperate, sealed against the entry of dirt and moisture, and having anupper end cover for the air cylinder which is capable of handling andaccepting large lateral loads. Yet another object is the provision of asupplementary telescoping lift cylinder adapted to substantiallyincrease the lifting height of the air jack. A further object is toprovide an air lift jack having a normally convexly curved bottom platewhereby the jack can be moved into position under the load with relativeease and very little effort.

Various further and more specific objects, features and advantages ofthe invention will appear from the description given below, taken inconnection with the accompanying drawings, illustrating by way ofexample a preferred form of the invention. Reference is here madeto thedrawings annexed hereto and forming an integral part of thisspecification, in which FIG. 1 is a side elevational view of the airlift jack of this invention positioned in lifting attitude under theload, on a very substantially reduced scale.

.FIG. 2 is an elevational view, partially in section, of the air liftjack of this invention.

FIG. 3 is a top plan view of the jack illustrated in FIG. 2.

FIG. 4 is a fragmentary vertical sectional view taken substantially onthe line 4-4 of FIG. 3.

FIG. 5 is a fragmentary elevational view, illustrating the telescopingarrangement of the supplementary lift cylinderand the main lift cylinderof the air jack.

The air lift jack 10 of this invention comprises the air cylinder 12,bottom plate 14, the radially corrugated top cover member 16, piston 18,piston return spring 20, main lift cylinder 22, lift pad 24 removablydisposed at and upon the distal end of the lift cylinder, handle 26affixed to the air cylinder body, and the air conduit fitting 28 to andwith which the air conduit 30 and manual valve 32 are removably securedand connected.

' The body 34 of air cylinder 12 is preferably made of steel tubing. Atits lower end, the edge of the cylinder body is disposed upon andweldingly secured and sealed to the bottom plate 14 so that a peripheralflange 36 extends outwardly beyond the wall of the air cylinder. Thebottom plate 14 is also made of steel and is provided with a convexlyformed or pre-stressed curved bottom crown portion 38 of relativelyslight thereby, the person carrying it will not ordinarily bumpcurvature but of sufficient height so that the axial central portion ofthe plate pivots upon a flat floor plane, allowing the air lift jack torotate, pivot or ride upon the curved central portion 38 and permittingfacile sliding of the jack into position under a load L to be raised.The diameter of the convexly curved portion 38 is substantially lessthan the diameter of the air cylinder body. The air lift jack can thusbe moved more easily or drawn more freely and with less effort upon theground floor plane A (FIG. 2), than would be possible with a perfectlyflat planar bottom plate. When the air lift jack is under load upon theground plane line A (FIG. 2),

the curved bottom crown portion 38 buckles or oil cans into the upperconcave attitude substantially represented by the broken line 40,allowing the air cylinder body to bear fully and directly upon the outeran integral steel casting and comprises the lower hub portion 42 securedwithin and to the upper end of the air cylinder 12 by screws 44, the hubflange 46 overlying the edge of the air cylinder, and the corrugatedcover portion 48 having the radial corrugations 50 extending from thecrown hub end 52 to the cover flange 46. The radially extendingcorrugations 50 give very substantial strength and support to the liftcylinder 22 against cocking as it rises and extends upwardly above thedistal edge of the crown end 52. A central bearing 54, integrally formedin the cover member,- extends from the crown hub end 52 to a planepassing substantially through the distal edge of the hub portion 42(FIG. 4). The hub end 52 is provided with a counterbore 55 seating arubber-type metal shrouded seal 57 pressed thereinto.

The piston 18 comprises a body 56 having a substantially medial annulargroove 58 in its outer edge filled with a ring seal 60 making pressurebearing sealing contact with the inner wall surface of the cylinder body34. The piston body 56 is also provided with a bottom seating pad 62 anda lift cylinder support hub 64 axially disposed on the other side of thepiston body and upon which the lift cylinder 22 is fixedly mounted, bywelding the lower end of the lift cylinder to the upper surface of thepiston body 56. The pad 62 and hub 64 are preferably integrally formedwith the piston body 56 as a steel casting.

The coiled tapered spring 20 has its base end at rest upon the uppersurface of the piston body 56 and its smaller end compressively bearingupon the inner surface of the radially corrugated portion 48 of thecover 16, adjacent the lift cylinder 22. The spring 20 biases the pistonto its bottoming position, with the seating pad-62 bearing upon theinner surface of the curved central portion 38 of the bottom plate 14,when air is released and discharged from the air cylinder 12 throughoperation of the manual control'valve 32; Although a coiledtaperingspring is illustrated and described above, it will be understood bypersons skilled in the art that equivalent means for biasing the pistonto its return bottom position may also be utilized in the combination ofthis air lift jack.

The lift cylinder 22 is preferably made of steel tubing and comprises abody 68 of cylindrical form, the proximal end of which is mounted andsupported upon the hub section 64 of the piston body 56 and is weldinglysecured to the face of the piston body, as described above andillustrated particularly in FIG. 2. The distal end of the lift cylinderhas an internal chamfer 69 and extends through and beyond the covermember 16, which supports it axially of the air cylinder, and isprovided with the readily removable lift pad 24 adapted to engage andcontact the load L to be raised. The lift cylinder body 68 is alsoprovided with transverse openings 70,70 through which a headed pin 72can be placed for securing the lift cylinder and pad in elevatedposition upon the cover hub end 52, upon release of air from the aircylinder 12, and also for securing the auxiliary lift cylinder 74 aswill be more fully described below.

The load-engaging lift pad 24 is of steel and provided with upwardlydirected edge flanges 78,78, and a hub portion 79 adapted to closelyseat within the distal end of the lift cylinder body 68. The topsurfaceconfiguration of the lift pad can of course be varied in designfor the load or loads to which the lift jack of this invention is morefrequently or regularly applied.

The handle 26 is of steel in a generally semi-circular ring formextending laterally from the air cylinder body 34 and secured to itsouter surface in a fixed substantially horizontal posture, preferably bywelding.

The air line fitting 28 is generally in the form of a fitting or nipple,the segment of a solid member, either rectilinear (as shown) or circularin cross-section, with a portion cut in a plane oblique to its topsurface so that the outer plane of the member 28 is at an angle obliqueto the base plane of the bottom plate 14 and is weldingly secured to theair cylinder body 34 closely adjacent the bottom plate flange 36. Whenfitting 28 has been affixed to the air cylinder body or wall 34, thefitting having a threaded bore 80 therethrough to threadedly receive andengage a suitable fitting 81 at the distal end of the air line conduit30, an air passage or opening 82 is drilled through the air cylinderwall 34 closely adjacent the bottom wall 14 and communicating with thethreaded bore 80 of fitting 28. Thus, when air is discharged into theair cylinder, it will be directed into the space under the piston body56 in the area of the seating pad 62 which raises the piston body aboveand from the inner surface of the bottom plate 14.

A clip 88 for storing the pin 72 is secured by one of the screws 44 tothe exterior of the air cylinder body 34.

The auxiliary lift cylinder 74 (FIG. 5) is provided with a cylindricalbody 90 adapted to telescope and closely fit and slide within thecylindrical body 68 of body 90 is provided with a coupling member 94secure-.

ly affixed thereto by welding or any other suitable means, the couplingmember extending substantially beyond the distal end of the body toprovide a support for the removable lift pad 24 which has its hubportion 79 seated therewithin. The auxiliary lift cylinder 74 is of suchlength that when the pin 72 is engaged in both lift members 22 and 74, asubstantial bearing portion 96 of auxiliary cylinder 74 extends throughthe cover member 16 and into the area of the air cylinder 12 to providefirm support against cocking as the lift pad 24 is raised and elevatedby piston 18.

The manually controlled air valve 32 is provided with a quick disconnectfitting 96 for an air supply conduit 98 connected to a source ofcompressed air serving the air space under the piston body 56 providedby the seating pad 62 which rests upon the bottom plate 14 in itsconvexly curved portion 38 on the ground line A (FIG. 2). As air underpressure charges into this air cylinder space, piston 18 is raisedagainst the biasing force of compression spring 20 to lift the cylinder22 and pad 24 against the load L, raising the same. When the load hasbeen raised to its desired height, the manual control valve 32 isreleased by the operator, causing the piston supported load to rest uponthe air cushion within the air cylinder 12 under the piston. The appliedload causes the convexly curved portion 38 of the bottom plate 14 to oilcan" inwardly to the posture represented generally by the line 40 (FIG.2), the peripheral flange 36 and annular portion 41 of the bottom plateresting fully upon the ground line A. The flange 36 and bottom plateportion 41 provide a substantially enlarged support area for the airlift jack under the load being carried by the lift pad, lift cylinderand piston.

Since the transverse openings 70,70 can be disposed in any positionlongitudinally of the lift cylinder body 68, the pin 72 can be insertedeither as a support or as a safety fitting against a drop of the liftcylinder upon the cushion of air supporting the piston 18. When the pinis so engaged, the lift cylinder can only fall or recede to the linewhere the pin 72 meets the upper cover element 52.

The auxiliary lift cylinder 74 is attached to the main lift cylinder 22by telescoping the bearing portion 96 within the body 68 of the mainlift cylinder until a pair of transverse openings 92,92 is aligned andin register with openings 70,70. The pin 72 is then passed through bothpairs of openings to lock the auxiliary lift cylinder and the main liftcylinder in fixed posture. The lift pad 24 is then transferred tocoupling 94, the lift pad hub portion 79 being seated securely in thebore at the distal end of the coupling.

As illustrated and described above, the spring 20 is of substantiallyheavy spring steel construction to more readily retract the piston to abottom position upon release of air pressure from the air cylinder 12.The cover member 16 has a substantially long bearing surface to moreadequately support the lift cylinder 22 and prevent its cocking underthe heavy loads carried thereby. Handle 26 is so located that a betterbalance of the jack is achieved as it is manually carried. Handle or rodmeans, for sliding the air lift jack under the load to a position moreremote than is shown in FIG. 1, can also be either removably or fixedlysecured to the air lift jack structure above disclosed. The air jack canbe manufactured in various lift heights, depending upon the loadapplications to which the jack will be put, yet the size of the air jackpermits easy storage in a minimum amount ofspace.

Additionally, the internal chamfer 69 at the distal end of the liftcylinder 22 removes any burrs at that edge which might cause thesupplementary or auxiliary lift cylinder 74 to stick or wedge in themain lift cylinder, and allows the auxiliary lift cylinder to seat morefully and release more readily.

The upper seal 57 in cover 16 is also significantly desirable when thelift jack 10 is used under farm tractors. Many tractor tires are loadedwith liquid chloride and when repairs are necessary for these tires,often the chloride spills from the tires upon the jack. Therefore,protection of the lift cylinders against corrosive attack is necessary.The seal 57 provides a large amount of this protection.

To assure a broader base of support in the lifting operation, the widerbase provided by the flanged bottom plate 14 helps to keep the lift jackfrom being pressed deeply into the ground when raising a farm tractor inthe field.

Although a particular preferred embodiment of the invention has beendisclosed herein for purposes of explanation, further modifications orvariations thereof, after study of this specification, will or maybecome apparent to those skilled in the art to which the inventionpertains. Reference should be had to the appended claims in determiningthe scope of the invention.

We claim:

1. An air operated lift jack comprising in combinationan air cylinder,

a piston operatively slidable in said air cylinder and having a bottomseating pad on the bottom side thereof,

and a lift cylinder support hub on the top side thereof,

a bottom base plate secured in air sealing relationship to the bottomedge of said air cylinder and having a peripheral flange extendingbeyond the perimeter of the air cylinder,

a flexible central axial portion provided with a normally convexlycurved bottom crown portion of relatively slight curvature but ofsufficient height that said portion pivots upon a flat ground plane,said central portion being adapted to flex upwardly and curve concavelywithin said air cylinder when said cylinder is charged with air and saidjack is in load supporting and elevating posture,

an integrally formed cover member for and secured to the top edge ofsaid air cylinder and having a plurality of downwardly tapering radialcorrugations extending from the upper crown end of said cover member toa peripheral flange adapted to overlie said air cylinder top edge,

a hub section of reduced diameter under said cover flange to which saidair cylinder top edge is secured, and a lift cylinder bearing ofsubstantial length axial and central of said cover,

a coiled piston return spring bearing upon said piston at one end andupon said cover at its other end to bias said piston to seated positionupon said bottom plate,

a tubular main lift cylinder fixedly secured at one end to said pistonand seated upon said support hub, disposed within said return spring,and extending through and beyond said cover bearing, said main liftcylinder having a pair of aligned transverse pin receiving openingstherein,

a pin adapted to be disposed in and through said main lift cylinderopenings,

a load lift pad removably seated upon the distal end of said main liftcylinder and having a hub portion adapted to fit slidingly within saiddistal end,

an air conduit coupling fitting fixedly secured to said air cylinder atthe lower end thereof adjacent said bottom plate peripheral flange andcommunicating with an air passageway through said air cylinder disposedin the plane of said piston bottom seating pad, so that air is admittedinto said air cylinder between said piston bottom side and said bottomplate,

and an air conduit having a manually operable control valve thereincommunicating with a source of 10 compressed air at one end and withsaid coupling fitting at its other end to provide an air supply to saidair cylinder. 7

2. The lift jack structure defined in claim 1, wherein said piston isformed as an integral unit with a body,

said bottom seating pad on one side and said lift cylinder support hubon the other side of said body, said seating pad and support hub beingsubstantially axial and central of said body.

3. The lift jack structure defined in claim 1, wherein said cover liftcylinder bearing extends from a plane passingsubstantially through thedistal edge of said hub section to the upper crown end of said covermember.

4; The lift jack structure defined in Claim 1, and including a handlefor manually carrying said lift jack secured to said air cylinderadjacent its upper edge and offset to one side thereof,

whereby when said lift jack is raised by said handle, the former pivotson said handle at an angle oblique to the ground plane.

5. The lift jack structure defined in claim 1, and including a tubularauxiliary lift cylinder having a cylindrical body adapted totelescopically fit and slide closely within said main lift cylinder, anda tubular coupling member secured to and extending from the distal endof said cylindrical body adapted to receive said load lift pad hubportion therein. 6. The lift jack structure defined in claim 5, whereinsaid auxiliary lift cylinder body is provided with at least one pair ofaligned transverse pin receiving openings adapted to come into registerwith said pair of main lift cylinder openings, whereby upon suchregistration said pin is seated through said openings to provide anextended lift cylinder for said lift jack.

7. The lift jack structure defined in Claim 5, wherein said auxiliarylift cylinder body is provided with a plurality of pairs of alignedtransverse pin receiving openings, each of said latter pairs of openingsadapted to come into register with said pair of main lift cylinderopenings, whereby upon any such registration said pinis seated throughsaid openings to provide a lift cylinder of extended height for saidlift jack.

8. The lift jack structure defined in claim 1, wherein said piston isprovided with an annular groove and a piston seal disposed in saidgroove for sealing said piston in sliding engagement with said aircylinder. 9. The lift jack structure defined in claim 1, and including Ia pm storage ring secured to said air cylinder adjacent said covermember peripheral flange. 10. The lift jack structure defined in claim1, and including aseal about said main lift cylinder in said covermember at its upper crown end, to seal said air cylinder and pistonagainst contamination.

1. An air operated lift jack comprising in combination an air cylinder,a piston operatively slidable in said air cylinder and having a bottomseating pad on the bottom side thereof, and a lift cylinder support hubon the top side thereof, a bottom base plate secured in air sealingrelationship tO the bottom edge of said air cylinder and having aperipheral flange extending beyond the perimeter of the air cylinder, aflexible central axial portion provided with a normally convexly curvedbottom crown portion of relatively slight curvature but of sufficientheight that said portion pivots upon a flat ground plane, said centralportion being adapted to flex upwardly and curve concavely within saidair cylinder when said cylinder is charged with air and said jack is inload supporting and elevating posture, an integrally formed cover memberfor and secured to the top edge of said air cylinder and having aplurality of downwardly tapering radial corrugations extending from theupper crown end of said cover member to a peripheral flange adapted tooverlie said air cylinder top edge, a hub section of reduced diameterunder said cover flange to which said air cylinder top edge is secured,and a lift cylinder bearing of substantial length axial and central ofsaid cover, a coiled piston return spring bearing upon said piston atone end and upon said cover at its other end to bias said piston toseated position upon said bottom plate, a tubular main lift cylinderfixedly secured at one end to said piston and seated upon said supporthub, disposed within said return spring, and extending through andbeyond said cover bearing, said main lift cylinder having a pair ofaligned transverse pin receiving openings therein, a pin adapted to bedisposed in and through said main lift cylinder openings, a load liftpad removably seated upon the distal end of said main lift cylinder andhaving a hub portion adapted to fit slidingly within said distal end, anair conduit coupling fitting fixedly secured to said air cylinder at thelower end thereof adjacent said bottom plate peripheral flange andcommunicating with an air passageway through said air cylinder disposedin the plane of said piston bottom seating pad, so that air is admittedinto said air cylinder between said piston bottom side and said bottomplate, and an air conduit having a manually operable control valvetherein communicating with a source of compressed air at one end andwith said coupling fitting at its other end to provide an air supply tosaid air cylinder.
 2. The lift jack structure defined in claim 1,wherein said piston is formed as an integral unit with a body, saidbottom seating pad on one side and said lift cylinder support hub on theother side of said body, said seating pad and support hub beingsubstantially axial and central of said body.
 3. The lift jack structuredefined in claim 1, wherein said cover lift cylinder bearing extendsfrom a plane passing substantially through the distal edge of said hubsection to the upper crown end of said cover member.
 4. The lift jackstructure defined in Claim 1, and including a handle for manuallycarrying said lift jack secured to said air cylinder adjacent its upperedge and offset to one side thereof, whereby when said lift jack israised by said handle, the former pivots on said handle at an angleoblique to the ground plane.
 5. The lift jack structure defined in claim1, and including a tubular auxiliary lift cylinder having a cylindricalbody adapted to telescopically fit and slide closely within said mainlift cylinder, and a tubular coupling member secured to and extendingfrom the distal end of said cylindrical body adapted to receive saidload lift pad hub portion therein.
 6. The lift jack structure defined inclaim 5, wherein said auxiliary lift cylinder body is provided with atleast one pair of aligned transverse pin receiving openings adapted tocome into register with said pair of main lift cylinder openings,whereby upon such registration said pin is seated through said openingsto provide an extended lift cylinder for said lift jack.
 7. The liftjack structure defined in Claim 5, wherein said auxiliary lifT cylinderbody is provided with a plurality of pairs of aligned transverse pinreceiving openings, each of said latter pairs of openings adapted tocome into register with said pair of main lift cylinder openings,whereby upon any such registration said pin is seated through saidopenings to provide a lift cylinder of extended height for said liftjack.
 8. The lift jack structure defined in claim 1, wherein said pistonis provided with an annular groove and a piston seal disposed in saidgroove for sealing said piston in sliding engagement with said aircylinder.
 9. The lift jack structure defined in claim 1, and including apin storage ring secured to said air cylinder adjacent said cover memberperipheral flange.
 10. The lift jack structure defined in claim 1, andincluding a seal about said main lift cylinder in said cover member atits upper crown end, to seal said air cylinder and piston againstcontamination.